The present disclosure relates to the use of non-wood alternative natural fibers in corrugated medium for containerboard packaging. A replacement of the conventional hardwood fiber is achieved by a hybrid fibrous composition that provides sufficient mechanical strength for containerboard packaging applications.
Traditionally pulp derived from fast growing trees, such as pine, has been used as the raw material for containerboard packaging. The containerboard includes linerboard and medium. The linerboard is usually made from softwoods, which have the longest fibers and produce the strongest containerboard. The medium is made from hardwood fibers, which tend to be shorter and stiffer than softwood fibers. In recent years, the use of recycled, old corrugated container (OCC) material has grown in popularity as a linerboard or corrugated medium because of concerns about environmental sustainability. The OCC, however, frequently requires repulping and de-inking processes. As such, the recycled fibers get shortened, weakened, and contaminated as the number of recycles increases. Coupled with an increased demand and use of recycled fiber by many corrugated cardboard producers, the cost of recycled fiber has also increased. The move toward single stream recycling is causing an increase in contamination (staples, plastic tapes, and hot melt adhesives) of and the mixing of fibers in the existing recovered fiber streams. Critical performance requirements such as strength (compression, edge crush, burst, and tensile strength), stiffness, rigidity, moisture resistance, grease resistance, and freeze/thaw tolerance can be more difficult to achieve with recycled paper or paperboard.
These approaches rely on tree-based fibers. The ability to use fibrous feedstock that grows in a shorter lifecycle and to use residuals from agricultural or industrial processing can help to fulfill corporate sustainability goals and reduce environmental impact on forests as well as carbon footprint (measured in eCO2 units).
Hybrid fiber compositions, including non-wood alternative natural fibers such as those derived from seaweed, algae, corn stover, wheat straw, rice straw, bamboo, kenaf, and the like, can be an option to resolve such aforementioned issues by creating tree-free products. Fiber substitution in corrugated medium using land-based non-wood alternative fibers such as wheat straw alone can be challenging at a high level of inclusion. One of the factors is related to the fines associated with pulp fibers. Wheat straw fiber contains more fines (about 38% to about 50%) than hardwood (about 20% to about 40%) or OCC (about 20% to about 25%) fibers. This being the case, wheat straw fiber dimensions (fiber length and diameter) are comparable to hardwood fibers, such as those pulped from maple and oak, but shorter than OCC fibers due to the presence of softwood fibers in recycled containerboard materials. The fines could be viewed as a filler; however, having more fines from wheat straw pulp compared to others does not contribute to strength.
A previous approach (see U.S. Pat. No. 1,829,852 to Darling) used chopped wheat straw (not a fiber per se) to make cardboard. In another approach (see U.S. Patent Publication No. 2006/0070295 to Huang and Peng) described a non-woody fiber (corn or wheat) mulching mat for weed control in agricultural plantation and cultivation. Finally, chitosan in addition to agricultural residual fibers was used to improve the flat crush resistance of a corrugating medium (see U.S. Pat. No. 4,102,738 to Dzurik).
Therefore, there exists a need for providing wood-alternative pulp materials to replace conventional fiber materials used in containerboard packaging. Additionally, there is a growing need for stronger, lighter weight corrugated materials that allow for packaging weight reduction. Although some previous efforts have attempted to use alternative fibers to produce construction- and furniture-applied composite boards, there is a lack of sustainable attempts to produce non-wood natural fiber-based corrugated medium to be used in containerboard packaging applications. As a result, the present disclosure fills such gaps by providing wood-alternative materials that can be used for environmentally-sustainable containerboard packaging.